Process for preparing light-colored long-chain olefin sulfonates

ABSTRACT

LIGHT-COLORED, LONG-CHAIN OLEFIN SULFONATES ARE PREPARED BY PRELIMINARILY TREATING LONG-STRAIGHT-CHAIN OLEFINS (8-24 C.) WITH A SMALL AMOUNT OF SO3 (0.5-20 MOL PERCENT BASED ON THE OLEFINS) DILUTED WITH AN INERT GAS AND THE RESULTING COLORED SUBSTANCES ARE REMOVED. THE REMAINDER OF THE LONG-STRAIGHT-CHAIN OLEFINS ARE TREATED WITH A LARGER AMOUNT OF SO3 (1.0-1.3 MOLS PER 1 MOL OF OLEFIN) DILUTED WITH AN INERT GAS, THE REACTION PRODUCT IS NEUTRALIZED AND THEN HYDROLYZED TO OBTAIN THE LIGHT-COLORED, LONGCHAIN OLEFIN SULFONATES.

PROCESS ;FOR PREPARING LIGHT-COLORED,

LONG-CHAIN OLEFIN SULFONATES KanjLMajimaand Kensuke Takei, Wakayama-shi, and Masaylikif ()ku, Kainan-shi, Japan, assignors to Kao Soap Co Ltd, Tokyo, Japan N Drawing". Filed Dec. 4, 1969, Ser. No. 882,277

Claims priority,'-application Japan Dec. 8, 1968,

-j- Ali/88,787 e i ,.Int. CL'C07c 143/16 U. S. -Cl. ;260. 513 v 4Claims ,A sTuAcTfiF THE DISCLOSURE light-colored,i lon'g-chain' olefin sulfonates are prepared by preliminarily treating long-straight-chain olefins (8-24 C.) with a small amount of S0 (0.5- mol percent basedion" the-olefins) diluted with an inert gas and the resulting colored substances are removed. The remainder of the long-straight-chain olefins are treated with alarger amount of S0 (1.0-1.3 mols per 1 mol of olefin) diluted with an inert gas, the reaction product is neutralized and then hydrolyzed to obtainthe light-colored, longchain olefin sulfonates.

The present invention relates to a process for preparing. 1igl1't'-colored, long-chain olefin sulfonates wherein longstraight-chain olefins are treated with a small amount of sulfur trioxide (S0 prior to the sulfonation, the resulting colored substances formed therein are removed and the thustreated olefins are then sulfonated with sulfur trioxide; 7

It is known in the art that olefin sulfonates, which are mainly composed of alkenybsulfonates, hydroxyalkane sulfonates and disulfonatesrmay be obtained by sulfonating 'long-straight-chain olefins with sulfur trioxide diluted with Jan inert-gas, particularly dry air or dry nitrogen gas, neutralizing the sulfonated products with an alkali if desired, .and hydrolyzing-the produced. sultones. For example, it has been disclosed in US. Pat. Nos. 2,061,617 to 2,061,620 and 2,094,451 as well as the Journal of the Arne'ricanfChemical Society, .76: 3952 (1964) and the Journal of the American .Oil Chemists Society, 40: 633 (1963 to prepare" monoolelin sulfonates from olefins by sulfonating the olefins with sulfur trioxide or other strong sulfonating agent and then hydrolyzing the reaction product. Howevenjolefinsulfonates thus prepared are colored yellowish brown. .or dark browndue to impurities contained in the. starting' olefins. That is to say, the color value ofa 10 yveightpercentaqueous solution of the ob tained olefin sulfonates exceeds 2000. Said color value or'Klet't number is expressed by the following equation in which the .adsorbance is measured with a 10 weight percent aqueousj'solution of olefin sulfonates at 420 m mama-use M v The purpo'se' of the present invention is to provide a process for sulfonating'olefinswhich makes it possible to lower the "colorval ueiof the obtained monolefin sulb e'lovvt abouffflQQfl "and, after bleaching, below anon-mo? 3,660,472 Patented May 2, 1972 We found that the colored substances which will be byproduced in the sulfonation of long-straight-chain olefins with sulfur trioxide are caused by the substances, other than olefins, contained in the olefin feed, which substances are more reactive with sulfur trioxide than the olefins and the sulfonates of which have high polarities and high boiling points. We have accomplished the present invention on the basis of the above findings.

According to the process of the present invention, a major portion of the impurities which will cause the coloring is changed into colored matters, in advance, by treating the starting long-straight-chain olefins with sulfur trioxide diluted with an inert gas in an amount suflicient for sulfonating a portion of the olefins. The produced colored matters may be selectively adsorbed and thereby removed from said olefins with an adsorbent such as active carbon since they have high polarities as compared with the olefins. Alternatively, since the colored matters have higher boiling points than the olefins, the colored matters can be removed as residues by distilling the treated olefins. Thus, in the process of the present invention, the colored matters may be removed from the olefins either by a distillation treatment or by an adsorption treatment.

The thus treated long-straight-chain olefins containing a reduced amount of impurities will be then sulfonated with sulfur trioxide diluted 'with an inert gas, neutralized with an alkali and the produced sultones will be then hydrolyzed to form olefin sulfonates, in a conventional manner known in the art. Thus, according to the process of the present invention, there may be obtained olefin sulfonates having a far lighter color than the color obtained when the pretreatment mentioned above is not conducted, and by further bleaching the sulfonates with a bleaching agent in a conventional manner known in the art, olefin sulfonates having a quite pale color may be obtained.

As olefins to be used in the process of the present invention, olefins containing straight-chain monoolefins having 8-24 carbon atoms as the main constituents may be used and the double bond of the olefin may be either terminal or internal. The starting olefins may contain branched monoolefins or straight or branched diolefins in an amount of less than 20 percent by weight. Among the olefins containing straight-chain monoolefins having 8-24 carbon atoms as the main constituents, there can be suitably used olefins containing straight chain monoolefins having 14-20 carbon atoms and, more preferably, 15-18 carbon atoms as the main constituents (more than weight per-cent). That is, the starting olefins are not necessarily pure and they can be prepared by any suitable method. These olefins can be obtained by the thermal cracking of paraffins, the dehydrogenation of paraflin hydrocarbons, the dehydrohalogenation of alkyl halides, polymerization of ethylenes, and the Fisher-Tropsch synthesis from carbon monooxide and hydrogen in the presence of a heavy metal catalyst such as Cu-Ni at an elevated temperature. The amount of sulfur trioxide to be used in the pretreatment of the present invention for the purpose of removing coloring impurities is suitably in the range of 0.5-20 molar percent and preferably 1-10 molar percent based on the olefins. The sulfur trioxide to be used in the pretreatment of the process of the present invention is suitably diluted with an inert gas (such as dry air or dry nitrogen) into a concentration in the range of 0.01-10 percent by volume prior to its contact with the olefins. After converting a major portion of color-causing impurities into colored matters, an adsorbent such as activated carbon, activated clay, bentonite, activated alumina, silica gel or diatomaceous earth is added in an amount of 2-20 percent by weight to the pretreated mixture. The

whole should be stirred thoroughly to adsorb the colored matters on the adsorbent and thereafter the adsorbent is separated by means of filtration or the like whereby the colored matters are also removed simultaneously.

In the above pretreatment of olefins with sulfur trioxide gas, the formation of not only colored matters but also alkenyl sulfonic acids and sultones will naturally occur. In case those compounds are formed in a relatively small amount, they can be adsorbed by the adsorbent and separated from the olefins together with the colored matters. On the other hand, when those compounds are formed in a relatively large amount, alkenyl sulfonic acids should be removed by washing with water from the olefins and sultones should be removed from the olefins by heating together with water or an alkali solution in order to hydrolyze them into water-soluble compounds and then by Washing with water. Thereafter the colored matters may be removed from the olefins by treating them with the above mentioned adsorbent. The colored matters may also be removed from the olefins by distillation.

The olefins after being treated by the above mentioned pretreatment steps are then sulfonated with 1.0-1.3 mols, per 1.0 mol of the olefins, of sulfur trioxide diluted with an inert gas (dry air, nitrogen or the like) into the concentration in the range of 1.0-l percent by volume. Immediately after the separation of the waste gas, the products are neutralized with an alkali solution (such as an aqueous solution of caustic soda) and the sultones contained therein are hydrolyzed in the presence of excess alkali, thus the desired olefin sulfonates being obtained. If the resulting olefin sulfonates are still dark in color for the desired use, they may be bleached with 0.1- percent by weight, based on the olefin sulfonates, of a bleaching agent such as sodium hypochlorite in a conventional manner known in the art.

Sulfur trioxide can be employed in its various forms, which include its stabilized forms, such as, for example, sulfan and liquid rat-modification, in the practice of the present invention. These liquid sulfur trioxides can be vaporized by any suitable means known in the art. As mentioned above, sulfur trioxide is used after diluting it with an inert gas such as air, oxygen, nitrogen, carbon dioxide, helium, argon, etc.

In the practice of the present invention, the reaction conditions in carrying out sulfonation of olefins are substantially same in the first pretreatment step and in the second sulfonation step and these conditions are substantially same as those conventionally used in the prior art sulfonation methods such as referred to above.

The temperature of sulfonation reaction is between 0 and 120 C, and the reaction pressure is /2 to 3 /2 atm.

The reaction is usually carried out at normal pressure. Since the reaction is an exothermic reaction, n0 additional hating is usually necessary. In most cases, it is necessary to remove excessive reaction heat by a suitable means and, therefore, it is desirable to maintain an optimum reaction temperature by cooling the reaction vessel.

The reaction time is highly dependent on such selected conditions as the concentration of the sulfonating agent and the type of reaction apparatus used. It is usually from 2 seconds to 120 minutes. In case the reaction mixture will be stirred vigorously by an appropriate mechanical device or it will be sprayed or in case a reaction apparatus of the thin film type or the annular clearance type is utilized, a particularly short reaction time can be attained. According to the type of reaction apparatus used, the reaction can be carried out either in a continuous system or in a batch system.

In hydrolyzing the sulfonation reaction product, the reaction mixture will be heated at a temperature of 80 to 300 C. and at a normal or increased pressure together with an excess acid or excess alkali aqueous solution. In this case, water in an amount sufficient to maintain the concentration of the sulfonation product in the aqueous solution in the range of 5 to 70 percent by weight should be used. This hydrolysis reaction will require usually 10 to 60 minutes at 4 atm., 150 C. It is preferable to carry out the hydrolysis in an alkaline solution, wherein the excess sulfonating agent should be first neutralized with an excess alkali and then the additional alkali should be supplied in an amount suflicient to neutralize the sulfonic acid to be produced. It is preferable to add the alkali in an amount in excess of up to 20 percent over the amount of alkali required theoretically. As the alkali agent to be used, hydroxides and carbonates of alkali metals, such as sodium and potassium and alkali earth metals; such as calcium and magnesium,are preferably. used. v

As mentioned above, in case the color of the obtained olefin sulfonate product should be further improved, a bleaching treatment can be carried out 'onthesulfonate product with a bleaching agent such as NaOCl and H 0 Since the olefin sulfonates obtained according to the method of the present invention contain aslight amount of colored substances, they can be easily removed by bleaching and the amount of the bleaching" agent to :be required is relatively small. a I

The light-colored olefin sulfonates obtained according to the process of the present invention have an excellent detergency effect and can be used as a component of a detergent composition in a conventional manner well known in the art.

COMPARATIVE EXAMPLE According to a conventional method, olefins (having an average molecular weight of 228) mainly composed of straight-chain tX-OlefiIlS having 15-18carbon atoms and 1.15 mols -(per 1.0 mol of olefins) of sulfur trioxide, diluted with dry air to a concentration of 3 percent by volume, were fed continuously and reacted together in a thin film type reactor provided with a cooling jackethThe products were neutralized with an aqueous solution of caustic soda and then hydrolyzed in the presence of excess caustic soda at 150 C. for 15 minutes. The hydrolyzed solution was adjusted to pH 9-10, to which was then added 1 percent and 3 percent by weight, based on the olefin sulfonates, of sodium hypochlorite, respectively, and the bleaching was effected at C. for 60 minutes.

The color of each product is given below by thecolor value (Klett number).

Color of non-bleached product f 2,300 Color of the product bleached with 1% NaOCl 650 Color of the product bleached with 3% NaOCl 350 EXAMPLE 1 Into a 5 l. flask provided with a stirrer, thermometer, inlet and outlet for gas, 2.28 kg. of the same olefins, as in the above Comparative Example were charged, to which were then fed respectively 0.5 molar percent, 1.0 percent, 5 percent, 10 percent and 20 percent, based on the olefins, of sulfur trioxide diluted with dry nitrogen gas to a concentration of 4 percentby volume through the gas inlet. The whole was stirred vigorously at room temperature to effect the contact and reaction of the gas with the olefins. In case the ratio of sulfur trioxide to the olefins was 0.5 molar percent, 45.6 g. of activated clay were added to the pretreated reaction mixture. In case the said ratio was 1.0 molar percent, 114 g. of activated clay were added. After stirring at room temperature for 60 minutes, the activated clay was filtered off. In case said ratio of sulfur trioxide to the olefins was 5 molar per cent, the reaction mixture was thoroughly washed with 5 percent aqueous solution of NaCl to remove substances soluble in water and 228 g. of activated clay wereadded to the mixture after drying. The whole was stirred at room temperature for 60 minutes and the clay was removed by filtration. In case the saidratios-of-sulfur trioxide to the olefins were 10 molar percent and20 molar percent, the respective reaction mixture was neutralized with an excess alkali and heated at C. for 20 minutes in order to hydrolyze sultones contained in the pretreating reaction mixture so as to convert said sultones into water-soluble substances. The mixture 'was then washed thoroughly with percent aqueous solution of NaCl. 456 g. of activated clay were added to the mixture. The whole was stirred at room temperature for 60 minutes and the clay was then removed by filtration.

The above five kinds of pretreated olefins were then sulfonated in completely the same manner as in the above Comparative Example to obtain olefin sulfonates and the color of each sulfonate product was examined before and after its bleaching by 1 percent and 3 percent NaOCl.

The results are shown below.

date the same apparatus as in Example 1, 2.28 kg. of the same olefins as in the above Comparative Example were charged, into which was then fed sulfur trioxide in the amount of 5 molar percent based on the olefins under the same condition as in Example 1 and the whole was allowed to react. The reaction mixture was washed thoroughly with 5 weight percent aqueous solution of NaCl to remove Water-soluble components from the mixture. The mixture was then dried and divided into three parts (1), (2) and (3).

7-6 g. of activated carbon were added to part (1) and 76 g. of activated clay were added to part (2), respectively, and both parts were stirred at room temperature for 60 minutes. Thereafter, the adsorbents were removed by way of filtration. As for part (3), the sultones contained therein were hydrolyzed in the presence of an alkali at 150 C. for 20 minutes and then removed by way of washing with water. Part (3) was then distilled under reduced pressure.

The three kinds of olefins treated in the above manner were sulfonated in completely the same manner as in the above Comparative Example to form olefin sulfonates.

The results were as shown in the following table.

The embodiments of the invention in which an exclufive property or privilege is claimed are defined as folows:

1. A process for preparing light-colored, long-chain olefin sulfonates, which comprises the steps of:

(I) contacting at a temperature in the range of 0 to 120 C. (A) an olefin feed consisting essentially of at least percent by Weight of straight-chain monoolefins having from 8 to 24 carbon atoms and the balance being branched monoolefins, straight-chain diolefins and branched diolefins, with (B) 1-10 molar percent, based on the olefin feed, of S0 gas diluted with an inert gas,

(II) removing the colored matters in the reaction product of step (I) by either (a) distilling said reaction product to recover, as the overhead fraction, a purified olefin substantially free of colored matters, or (b) contacting said reaction product with an absorbent selected from the group consisting of activated carbon, actviated clay, bentonite, activated alumina, silica gel and diatomaceous earth, and then removing from said reaction product the absorbent containing absorbed colored matters to obtain a purified olefin substantially free of colored matters,

(111) then sulphonating said purified olefin at a temperature in the range of 0 to C., with from 1.0 to 1.3 moles, per one mol of the purified olefin, of S0 diluted with an inert gas, and

(IV) neutralizing the sulphonated product of step III with an alkali and then hydrolyzing the sultones contained in the sulphonated product to obtain the olefin sulfonates.

2. The process as claimed in claim 1, in which said inert gas is selected from the group consisting of dry air and dry nitrogen.

3. The process as claimed in claim 2, in which said sulfur trioxide is diluted to a concentration in the range of 0.01-10 percent by volume prior to its contact with the olefins.

4. The process as claimed in claim 1, in which the obtained olefin sulfonates are bleached with 0.1-5 percent by weight based on the olefin sulfonates, of sodium hypochlorite.

References Cited UNITED STATES PATENTS 1/1970 Garner et al. 260-513 R 1/ 196-9 Baumann et al. 260-513 R 

